1. Field of the Invention
The present invention relates to opening and closing mechanisms used in a range of electronic devices such as mobile phones and personal computers, and also relates to electronic devices using the opening and closing mechanisms.
2. Background Art
With electronic devices such as mobile phones and personal computers becoming increasingly smaller and lighter, many products are adopting designs that attach a movable housing to a fixed housing in an openable and closable fashion, a so-called folding design. The opening and closing mechanisms used in these folding electronic devices are also required to be downsized while ensuring reliable opening and closing operations.
A conventional opening and closing mechanism is described next with reference to FIGS. 4 and 5. In the drawings, a sectional view is radially enlarged for easier understanding of the relation between a fixed cam and a movable cam.
FIG. 4 is a sectional view and FIG. 5 is an exploded perspective view of the conventional opening and closing mechanism. In the drawings, roughly cylindrical fixed member 51 is made of metal, and fixing section 51A is formed on its left side face. A pair of fixed cams 52 are formed on the periphery of a right side face of this fixed member 51. Each of these fixed cams 52 includes protrusion 52A and two sloped portions 52B and 52C extending upward and downward from protrusion 52A.
Movable member 53 is also roughly cylindrical and made of metal. This movable member 53 is disposed in a rotatable fashion in opening and closing directions and also in an axially-movable fashion relative to fixed member 51. A pair of movable cams 54 are provided on the periphery of a left side face of movable member 53, which is an opposing face to fixed cams 52.
Case 55 is roughly cylindrical and made of metal. Fixed member 51 and movable member 53 are housed in this case 55. Spring 56 is slightly compressed and placed between latching part 53A on a right side face of movable member 53 and an inner side face of case 55. This spring 56 applies a leftward force to movable member 53, and thus tips of movable cams 54 resiliently contact sloped portions 52B of fixed cams 52.
Furthermore, a left end of roughly columnar fixed shaft 57 is secured to fixed member 51. Fixing section 51A of this fixed member 51 rotatably protrudes from a left side face of case 55. A right end of fixed shaft 57 passes through a hollow portion of movable member 53 and spring 56, and is rotatably attached to an outer side face of case 55 by stopper ring 58, configuring opening and closing mechanism 60.
Opening and closing mechanism 60 as configured above is assembled in an electronic device such as a mobile phone (not illustrated). Fixing section 51A of fixed member 51 is attached to a fixed housing (not illustrated) where keys, a microphone, and so on are formed. Case 55 is attached to a movable housing (not illustrated) where a display, speaker, and so on are formed. With this opening and closing mechanism 60, the movable housing is supported relative to the fixed housing in an openable and closable fashion, configuring the electronic device.
In the above structure, spring 56 applies a force in a closing direction to movable member 53 when the tips of movable cams 54 are resiliently contacting lower sloped portions 52B of fixed cams 52, as shown in FIG. 4. The movable housing, to which case 55 is attached, is thus retained in a closed state relative to the fixed housing.
When the movable housing is opened by hand from this closed state, case 55 attached to the movable housing rotates, and movable member 53 rotates as it moves in the axial direction inside case 55. The tips of movable cams 54 then ride over protrusions 52A of fixed cams 52, and resiliently contact upper sloped portions 52C. This applies a force in an opening direction to movable member 53, and thus this force applies a force in the opening direction to the movable housing. Accordingly, the movable housing is opened at a predetermined angle relative to the fixed housing.
In other words, movable member 53, which has a force imparted thereto by spring 56, is moved in an axial direction by rotating case 55 attached to the movable housing. This makes the tips of movable cams 54 resiliently contact either sloped portions 52B or sloped portions 52C of fixed cams 52, resulting in opening and closing of the movable housing relative to the fixed housing.
One prior art configuration related to the present invention is disclosed in Japanese Patent Unexamined Publication No. 2004-245342.
In order to make the entire size of the above conventional opening and closing mechanism smaller, components such as movable cam 54, fixed cam 52, and spring 56 need to be made smaller. However, these components require a certain degree of size and load in order to ensure reliable opening and closing operations. Accordingly, downsizing of the prior art is difficult.